/**
 * SQL-DK
 * Copyright © 2013 František Kučera (frantovo.cz)
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, version 3 of the License.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 */
package info.globalcode.sql.dk;

import static info.globalcode.sql.dk.Functions.findByName;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;
import java.util.logging.Level;
import java.util.logging.Logger;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import java.util.regex.PatternSyntaxException;

/**
 * Has named parameters.
 *
 * @author Ing. František Kučera (frantovo.cz)
 */
public class SQLCommandNamed extends SQLCommand {

	private static final Logger log = Logger.getLogger(SQLCommandNamed.class.getName());
	private String namePrefix;
	private String nameSuffix;
	private List<NamedParameter> parameters;
	private List<NamedParameter> parametersUsed = new ArrayList<>();
	private StringBuilder updatedQuery;
	private Pattern pattern;
	private SQLCommandNumbered numbered;

	public SQLCommandNamed(String query, List<NamedParameter> parameters, String namePrefix, String nameSuffix) {
		super(query);
		this.updatedQuery = new StringBuilder(query.length());
		this.parameters = parameters;
		this.namePrefix = namePrefix;
		this.nameSuffix = nameSuffix;
	}

	@Override
	public PreparedStatement prepareStatement(Connection c) throws SQLException {
		return getSQLCommandNumbered().prepareStatement(c);
	}

	@Override
	public void parametrize(PreparedStatement ps) throws SQLException {
		getSQLCommandNumbered().parametrize(ps);
	}

	private void prepare() throws SQLException {
		try {
			buildPattern();
			placeParametersAndUpdateQuery();
			logPossiblyMissingParameters();
		} catch (PatternSyntaxException e) {
			throw new SQLException("Name prefix „" + namePrefix + "“ or suffix „" + nameSuffix + "“ contain a wrong regular expression. " + e.getLocalizedMessage(), e);
		}
	}

	/**
	 * @return SQL command with named parameters converted to SQL command with numbered parameters
	 */
	public SQLCommandNumbered getSQLCommandNumbered() throws SQLException {
		if (numbered == null) {
			prepare();
			numbered = new SQLCommandNumbered(updatedQuery.toString(), parametersUsed);
		}

		return numbered;
	}

	/**
	 * Builds a regexp pattern that matches all parameter names (with prefix/suffix) and which has
	 * one group: parameter name (without prefix/suffix)
	 */
	private void buildPattern() throws PatternSyntaxException {
		StringBuilder patternString = new StringBuilder();

		patternString.append(namePrefix);
		patternString.append("(?<paramName>");
		for (int i = 0; i < parameters.size(); i++) {
			patternString.append(Pattern.quote(parameters.get(i).getName()));
			if (i < parameters.size() - 1) {
				patternString.append("|");
			}
		}
		patternString.append(")");
		patternString.append(nameSuffix);

		pattern = Pattern.compile(patternString.toString());
	}

	private void placeParametersAndUpdateQuery() {
		final String originalQuery = getQuery();
		Matcher m = pattern.matcher(originalQuery);

		int lastPosition = 0;
		while (m.find(lastPosition)) {
			String name = m.group("paramName");

			updatedQuery.append(originalQuery.substring(lastPosition, m.start()));
			updatedQuery.append("?");

			parametersUsed.add(findByName(parameters, name));

			lastPosition = m.end();
		}
		updatedQuery.append(originalQuery.substring(lastPosition, originalQuery.length()));

		for (NamedParameter definedParameter : parameters) {
			if (findByName(parametersUsed, definedParameter.getName()) == null) {
				/**
				 * User can have predefined set of parameters and use them with different SQL
				 * queries that use only subset of these parameters → just warning, not exception.
				 */
				log.log(Level.WARNING, "Parameter „{0}“ is defined but not used in the query: „{1}“", new Object[]{definedParameter.getName(), originalQuery});
			}
		}
	}

	private void logPossiblyMissingParameters() {
		Pattern p = Pattern.compile(namePrefix + "(?<paramName>.+?)" + nameSuffix);
		Matcher m = p.matcher(updatedQuery);
		int lastPosition = 0;
		while (m.find(lastPosition)) {
			/**
			 * We have not parsed and understood the SQL query; the parameter-like looking string
			 * could be inside a literal part of the query → just warning, not exception.
			 */
			log.log(Level.WARNING, "Possibly missing parameter „{0}“ in the query: „{1}“", new Object[]{m.group("paramName"), getQuery()});
			lastPosition = m.end();
		}
	}

	@Override
	public List<NamedParameter> getParameters() {
		return parameters;
	}
}